slapos_jio: make Organisation_hasItem consistent

   Rely on the proper API to exclude cases that aren't shown on the view listbox.

master/bt5/slapos_jio/SkinTemplateItem/portal_skins/slapos_hal_json_style/Organisation_hasItem.py

 import json
-kw = {"node_uid": context.getUid(),
-      "at_date": DateTime(),
-      "limit": 1}
-
-return json.dumps(len(context.portal_simulation.getCurrentTrackingList(**kw)))
+return json.dumps(len(context.Organisation_getComputeNodeTrackingList()))